Apple's 'microslot antennas' are invisible to the naked eye, could see use in future iPhones

Apple on Tuesday won the patent rights to "microslot antenna" technology that allows micron-wide antenna assets to be integrated into the housing of a portable device, such as an iPhone, making them nearly invisible to the human eye.

Apple's microslot antennas as seen on a laptop computer. | Source: USPTO

As portable electronics become thinner and more compact with each successive generation, internal space is quickly becoming a limiting factor to device designers. Apple's U.S. Patent No. 8,373,610 for "Microslot antennas for electronic devices," granted by the U.S. Patent and Trademark Office on Tuesday, could drastically cut down on the size of at least one component needed to create products like the iPhone.

While the patent refers to implementations in a laptop computer, the antenna tech can be used in other portable electronics like smartphones and tablets.

With Apple's current technology as seen in the iPhone 5, two internal radio antennas dynamically switch between multiple frequency bands, including those carrying fast LTE data. In order to fit the units within the handset's slim body, Apple had to design a window for radio waves, while keeping the unit small enough to leave room for other important structures like the logic board and battery.

Tuesday's patent focuses on so-called "microslot antenna" technology, or "dielectric-filled microslots that are formed in a ground plane element." According to the invention, the ground plane can be a device's housing as long as it is conductive, meaning the slots would be integrated on the outer hull of a product. The system can also support multiple communications bands, meaning functionality would not be compromised for size enhancements.

Illustration of microslot antenna arrangement in a device housing.

As for the size of the microslots, the patent language states that the widths of the slots are usually significantly less than their lengths. For example, widths can range from microns to hundreds of microns, while a microslot's length can be on the order of millimeters or centimeters.

Filling the slots is a dielectric such as epoxy, plastic, air or other suitable substance that prevents foreign matter from entering. Antenna feeds can be located at or between the functional microslots, and operate on common communication bands that support Wi-Fi, Bluetooth, GPS and 3G cellular, among others.

Illustration of feed terminal (70) and microslots (92).

The '601 property was first filed for in December 2007, less than six months after the original iPhone debuted, and credits Bing Chiang, Gregory Allen Springer, Douglas B. Kough, Enrique Ayala and Matthew Ian McDonald as its inventors.

A phone could have an aluminum (or Liquid Metal!) case back, with tiny ( down to .005 inch wide) plastic filled slots that serve as the antennas. Solves a lot of space problems, being able to use a metal case like that.

My question to any manufacturing engineers reading this, is how the heck do you make slots that small in such materials? Lasers? Water jets? Tiny saws? Just mold them in? I'm curious. Thanks for any info!

(This reminds me of an anecdote from the middle of the Cold War. Wishing to prove that Communism worked, an East Germany lab sent an sample of an incredibly fine wire to another lab in West Germany. It was just about the smallest wire ever made. The West Germans bored a hole down its middle to make it into a tube and sent it back.)

It's also interesting that the inventors getting this patent at Apple, are an entirely different group than the ones who designed the iPhone 4 bezel antenna (which was also a form of a slot antenna).

My question to any manufacturing engineers reading this, is how the heck do you make slots that small in such materials? Lasers? Water jets? Tiny saws? Just mold them in? I'm curious. Thanks for any info!

A phone could have an aluminum (or Liquid Metal!) case back, with tiny ( down to .005 inch wide) plastic filled slots that serve as the antennas. Solves a lot of space problems, being able to use a metal case like that.

My question to any manufacturing engineers reading this, is how the heck do you make slots that small in such materials? Lasers? Water jets? Tiny saws? Just mold them in? I'm curious. Thanks for any info!

(This reminds me of an anecdote from the middle of the Cold War. Wishing to prove that Communism worked, an East Germany lab sent an sample of an incredibly fine wire to another lab in West Germany. It was just about the smallest wire ever made. The West Germans bored a hole down its middle to make it into a tube and sent it back.)

It's also interesting that the inventors getting this patent at Apple, are an entirely different group than the ones who designed the iPhone 4 bezel antenna (which was also a form of a slot antenna).

Is that story true?

This bot has been removed from circulation due to a malfunctioning morality chip.

I didn't say they were exactly the same. I said they're both forms of the same basic category of antenna, which they are.

ROTFLMAO.

So is this:

You really need to learn something about patents. EVEN IF your claim that they're both similar were true, it doesn't make Apple's invention unpatentable. Only if the specific claims of the new patent were covered by prior art would the patent be invalidated. And the iPhone 4's antenna isn't anywhere near the claims of this patent.

"I'm way over my head when it comes to technical issues like this"Gatorguy 5/31/13

My question to any manufacturing engineers reading this, is how the heck do you make slots that small in such materials? Lasers? Water jets? Tiny saws? Just mold them in? I'm curious. Thanks for any info!

Photolithography and chemical etching (used for PCBs) can easily do 5 mil features/spacing.

Photolithography and chemical etching (used for PCBs) can easily do 5 mil features/spacing.

Not a very efficient method when you would have to apply (expose, and then remove) photo-resist across the entire surface of a complex 3D housing. Also, when etching slots of any significant depth undercutting would be a problem.

I didn't say they were exactly the same. I said they're both forms of the same basic category of antenna, which they are.

Please explain why you think they are not both slot antennas.

(I've studied both patents, and have especially researched the bezel one over the past few years.)

One is a large antenna made up of a large piece of metal on the outside of a phone that surrounds the phone, the other is a tiny antenna etched on the inside surface of the shell of a phone. They are wildly different in implementation at best.

I didn't say, that you said, that they were "exactly" the same, so we seem to be arguing semantics and basically having a disagreement on tone (I'm reading a wee bit of condescension into yours). They might be technically in the same category, they clearly have elements in common, but it's equally clear they are very different in several ways as well.

I got the clear implication from your first post that they are basically "the same thing," which seems ridiculous to me.

I'm already having trouble caring about this topic enough to write this rebuttal however, so ... you win?

Hopefully, this'll encourage Apple to add GPS chips to their entire product line from the iPod touch to the non-WiFi iPad and all their laptops. Every Apple product should be location aware. That'd be marvelous for app developers and users.

No. It's not. That would demonstrate a lack of understanding of basic antenna types.

You really need to learn something about patents. EVEN IF your claim that they're both similar were true, it doesn't make Apple's invention unpatentable. Only if the specific claims of the new patent were covered by prior art would the patent be invalidated. And the iPhone 4's antenna isn't anywhere near the claims of this patent.

No one's talking about patentability.

I simply gave a piece of what I thought was interesting information that most people ( obviously including yourself) are unaware of... that the same basic design principle is used in both antennas.

Quote:

Originally Posted by Gazoobee

One is a large antenna made up of a large piece of metal on theoutsideof a phone that surrounds the phone, the other is a tiny antenna etched on theinsidesurface of the shell of a phone. They are wildly different in implementation at best.

Yet they're still the same basic antenna technology.

As I said, I think it's really cool, myself. Slot antennas have been used for years in cell towers and phones, but using the case itself as the main component... instead of hiding it inside... is pretty neat.

--

To all those who answered my question about construction: many thanks!

Very likely, yes. I first read about it as a kid in Popular Science, if I recall correctly.

Years later, I became an Electronic Warfare specialist in the USASA, which was the military branch of NSA at the time. (I spent a lot of time with antennas there, and it is why I took EE as a major when I got out.)

One of the many things I got to do, was work in TAREX (Target Exploitation) for a while. In wartime, TAREX personnel go over captured documents looking for codes, operating manuals, etc. In peacetime, they travel to other countries and bring back photos of antennas, installations, and any other information they can find, such as checking used book stores for technical manuals.

Anyway, you'd be surprised at how many times opposing sides would exchange information on purpose (or "allow" stuff to be "stolen"). Sometimes to try to awe the other side. More often, to try to confuse your enemy as to your real capabilities or intentions.

The upshot is: yes sir, for many reasons, I believe it really happened.

Very likely, yes. I first read about it as a kid in Popular Science, if I recall correctly.

Years later, I became an Electronic Warfare specialist in the USASA, which was the military branch of NSA at the time. (I spent a lot of time with antennas there, and it is why I took EE as a major when I got out.)

One of the many things I got to do, was work in TAREX (Target Exploitation) for a while. In wartime, TAREX personnel go over captured documents looking for codes, operating manuals, etc. In peacetime, they travel to other countries and bring back photos of antennas, installations, and any other information they can find, such as checking used book stores for technical manuals.

Anyway, you'd be surprised at how many times opposing sides would exchange information on purpose (or "allow" stuff to be "stolen"). Sometimes to try to awe the other side. More often, to try to confuse your enemy as to your real capabilities or intentions.

The upshot is: yes sir, for many reasons, I believe it really happened.

It's a great story but I can't help but be skeptical. Not that you didn't read it; in no way do I think you made it up, but something about this story has a feeling of implausibility about it. Something I've picked up from studying etymology is that the more fantastical the story the more likely it is to have been fabricated. That is to say that it is in any way false but something about it seems too convenient to be accurate.

PS: I'm very likely to be using that story in the future. A good anecdote is a good anecdote.

This bot has been removed from circulation due to a malfunctioning morality chip.

It's a great story but I can't help but be skeptical. Not that you didn't read it; in no way do I think you made it up, but something about this story has a feeling of implausibility about it. Something I've picked up from studying etymology is that the more fantastical the story the more likely it is to have been fabricated. That is to say that it is in any way false but something about it seems too convenient to be accurate.

PS: I'm very likely to be using that story in the future. A good anecdote is a good anecdote.

Something I've picked up from studying etymology is that the more fantastical the story the more likely it is to have been fabricated. That is to say that it is in any way false but something about it seems too convenient to be accurate.

I can understand your reasons to be suspicious precisely because it's such a good story.

It's like another thing I learned: never ascribe something bad as being part of a hidden conspiracy, if the action can more easily be explained by sheer stupidity or laziness!

At the same time, I can tell you that there are many, many such stories in the Intel realm, and most of them spring from something that really happened, even if the details were modified to hide the source.

No, but a well known joke here in Germany. Actually the joke goes like this: Proud of what they beleive is the thinnest wire ever made they send it to Russia for measuring its thickness. It comes back with a note saying "Sorry, it's too thin for us to measure". So they decide to send it to China. Same result. Finally they decide to send it to Western Germany. Nothing for weeks, then it comes back with a note "We did not know what to do with the wire, so we made it a tube and cut a thread on the outside as well. We hope this is in your interest." ;-)

Edit: Posted before finished reading the thread. Just saw it has been covered.

It can't be Liquid Metal as that is a cast material and wouldn't be capable of being etched after the fact as the patent describes.

The patent description notes that slots can either be etched in a circuit board, or ...

" Other techniques may be used when forming microslots in conductive housing walls.For example, microslots may be machined in metal walls or other conductive wall structures in housing using laser cutting, plasma arc cutting, micromachining (e.g., using grinding tools), or any other suitable techniques."